Large commercial vessels traveling through navigable waters will occasionally pass over ropes that become suspended in the water based on the material from which the ropes are made. As these vessels pass over the rope, often it becomes entangled in the propeller.
The rope wraps itself around the propeller, balling around the propeller and shaft, causing (1) the shaft to break and the propeller to sink, or (2) the shaft to be drawn out of the vessel and the propeller to sink and be lost, causing a significant financial loss, and often substantially delaying when the vessel can get back up underway again.
However, to cure these problems, the preferred rope cutting and propeller hitch device of the present invention prevents the rope from staying wrapped and balled around the propeller and/or shaft by cutting it into non-entangling segments, retains the propeller should the shaft break, and keeps the shaft from being drawn out of the vessel.
A listing of prior patents, which may be relevant to the invention, is presented below:
______________________________________ U.S. Pat. No. Patentee(s) Issue Date ______________________________________ 0,067,982 Hudson 20 Aug 1867 0,425,019 Bower, et al 08 Apr 1890 1,649,657 Blake 15 Nov 1927 2,319,947 Oswood 25 May 1943 2,690,728 Cavanaugh 05 Oct 1954 3,467,052 Hadler 16 Sept 1969 4,246,862 Deal 27 Jan 1981 4,447,214 Henrich 08 May 1984 4,447,215 Govan 08 May 1984 4,450,670 Robinson 29 May 1984 4,507,091 Govan 26 Mar 1985 4,544,363 Govan 01 Oct 1985 4,578,040 Sumino et al 25 May 1986 4,594,108 4,609,361 Sumino et al 02 Sept 1986 4,676,758 Dennis 30 Jun 1987 4,718,871 Mendelevitch 12 Jan 1988 4,801,281 Govan 31 Jan 1989 4,898,552 Cochran 06 Feb 1990 4,911,664 Gremillion 27 Mar 1990 4,938,724 Shaw 03 Jul 1990 4,943,249 Govan 24 Jul 1990 4,954,108 Govan 04 Sept 1990 5,007,867 Kelley 16 Apr 1991 5,017,167 Govan 21 May 1991 5,052,957 Govan 01 Oct 1991 5,807,150 Minter, Sr. 15 Sep 1998 ______________________________________
The broad concept of using a cutting edge to clear a screw prop goes as far back as at least as 1867 (note U.S. Pat. No. 67,982; note also U.S. Pat. No. 425,019 of 1890).
The most prolific inventor in the field appears to be Donald T. Govan of Ft. Lauderdale, Fla., who has been granted at least eight patents ('215, '091, '363, '281, '249, '108, '167 & '957).
A pertinent patent is the patent to Minter (U.S. Pat. No. 5,807,150) directed to a blade system for cutting weeds and other aquatic vegetation on a marine motor (e.g. a trolling motor). The Minter patent discloses the use of a series of backwardly directed, generally longitudinally extending series of blade bodies 7 peripherally spaced about the screw prop shaft with edge cutting surfaces or serrations 11, with each of the blades 7 mounted at an angle to the center line on a ramp or wedge shaped mount 2 with the cutting edge of the blade facing tangentially. The above referenced patents show a number of different approaches for clearing lines or cutting away aquatic vegetation, using various type of cutting or grinding surfaces, some having similarities to the invention.
As will be seen more fully below, the present invention is substantially different in structure, methodology and approach from that of the prior patents.